Island



(No Model.) I Y J. U. TAFT.

METHOD OF GROOVING DRILL BLA'NKS. v No. 434,139. Patented Aug. 12, 1890.

UNITED STATES ATENT FFICE.

JEROME C. TAFT, OF PROVIDENCE, RHODE ISLAND.

METHOD OF GRQOVING DRlLL-BLANKS.

SPECIFICATION forming part of Letters Patent No. 434,139, dated August12, 1890.

- Application filed April 22, 1890- Serial lie. 34:9,006. (N0 modeL) Toall whom it may concern:

Be it known that I, JEROME C. TAFT, a citizen of the United States,residing at Provideuce, in the State of Rhode Island, have invented anew and useful Improvement in the Method of Grooving Drill-Blanks, ofwhich the following is a specification.

In the manufacture of grooved drills from a bar of steel having squaredends, by the process of cold-swaging, it has been found that as theresult of the said process the end of the grooved drill-blank would bealmost invariably split or cracked, thus necessitating the cutting offand loss of aconsiderable portion of the stock; and it is the object ofmy invention to avoid this difficulty; and to that end my inventionconsists in providing the drill-blank with atapering or pointed endprior to the complete swaging of the blank to form the clearing-groovesof the drill, as hereinafter set forth.

Figure 1 represents a side View of a cylindrical drill-blank providedwith a tapered or pointed end. Fig. 2 represents the grooveddrill-blank, formed from the blank shown in Fig. 1 by the process ofcold-swaging between sets of oppositely-reciprocated dies. Fig. 3represents a front elevation of the sets of swaging-dies, by means ofwhich the clearing grooves of the drill-blank may be formed, the groovedblank being shown in transverse section between the dies. Fig. 4represents a front elevation of a rotary swaging-machine, in which thedies as shown in Fig. 3, can be employed, the front plates which serveto hold the dies in place being removed.

I11 the accompanying drawings, A, Fig. 1, represents a suitable bar ofsoft steel, which may either first be provided with a pointed end I), orbe provided with said pointed end when the blank is partly swaged, aspreferred. The pointed blank is to be inserted into the opening abetween the sets of oppositely-reciprocating swaging-dies o c d d, whichsets of dies are arranged at right angles to each other, and which maybe operated simultaneously by engagement with the heaters e e e c of theswaging-machine, as shown in Fig. at, and the clearing-grooves f f ofthe drill may be formed by gradually closing the reciprocatedgrooving-dies upon the blank; and to accomplish the formation of thegrooves to the best advantage I preferably employ several removable diesof gradually-changing form to carry the clearing-grooves f f to theproper depth from the original cylindrical or other form of the blank;but in some cases the said grooves can be completely made without achange of dies, especially in the manufacture of drills of small size.The pointed end, when made prior to the completed action of the sets ofswaging-dies upon the blank, will tend to prevent the cracking of themetal at the end of the blank, by reason of which cracking aconsiderable loss is entailed in the manufacture.

I claim as my invention The method of grooving drill-blanks, whichconsists in cold-swaging the blanks between sets ofoppositoly-reciprocated swaging-dies to form the clearing-grooves, andproviding the drill-blank with a pointed end prior to the completeswaging of the grooves, as set forth.

JEROME C. TAFT. Witnesses: JOHN S. LYNCH, SOCRATES SCHOLFIELD.

